Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.115.2.1
1.1 deraadt 1: /*
1.39 deraadt 2: * Author: Tatu Ylonen <ylo@cs.hut.fi>
3: * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
4: * All rights reserved
5: * Code to connect to a remote host, and to perform the client side of the
6: * login (authentication) dialog.
1.78 deraadt 7: *
8: * As far as I am concerned, the code I have written for this software
9: * can be used freely for any purpose. Any derived versions of this
10: * software must be clearly marked as such, and if the derived work is
11: * incompatible with the protocol description in the RFC file, it must be
12: * called by a name other than "ssh" or "Secure Shell".
1.39 deraadt 13: */
1.1 deraadt 14:
15: #include "includes.h"
1.115.2.1! jason 16: RCSID("$OpenBSD: sshconnect.c,v 1.119 2002/01/21 15:13:51 markus Exp $");
1.1 deraadt 17:
1.66 markus 18: #include <openssl/bn.h>
1.71 markus 19:
1.91 markus 20: #include "ssh.h"
1.1 deraadt 21: #include "xmalloc.h"
22: #include "rsa.h"
1.59 markus 23: #include "buffer.h"
1.1 deraadt 24: #include "packet.h"
25: #include "uidswap.h"
1.21 markus 26: #include "compat.h"
1.58 markus 27: #include "key.h"
1.71 markus 28: #include "sshconnect.h"
1.58 markus 29: #include "hostfile.h"
1.91 markus 30: #include "log.h"
31: #include "readconf.h"
32: #include "atomicio.h"
33: #include "misc.h"
1.115.2.1! jason 34: #include "readpass.h"
1.51 markus 35:
1.70 markus 36: char *client_version_string = NULL;
37: char *server_version_string = NULL;
1.59 markus 38:
1.43 markus 39: extern Options options;
1.50 markus 40: extern char *__progname;
1.91 markus 41:
1.110 markus 42: static const char *
43: sockaddr_ntop(struct sockaddr *sa)
44: {
45: void *addr;
46: static char addrbuf[INET6_ADDRSTRLEN];
47:
48: switch (sa->sa_family) {
1.115.2.1! jason 49: case AF_INET:
! 50: addr = &((struct sockaddr_in *)sa)->sin_addr;
! 51: break;
! 52: case AF_INET6:
! 53: addr = &((struct sockaddr_in6 *)sa)->sin6_addr;
! 54: break;
! 55: default:
! 56: /* This case should be protected against elsewhere */
! 57: abort(); /* XXX abort is bad -- do something else */
1.110 markus 58: }
59: inet_ntop(sa->sa_family, addr, addrbuf, sizeof(addrbuf));
60: return addrbuf;
61: }
62:
1.39 deraadt 63: /*
64: * Connect to the given ssh server using a proxy command.
65: */
1.109 itojun 66: static int
1.103 markus 67: ssh_proxy_connect(const char *host, u_short port, struct passwd *pw,
1.3 provos 68: const char *proxy_command)
1.1 deraadt 69: {
1.38 markus 70: Buffer command;
71: const char *cp;
72: char *command_string;
73: int pin[2], pout[2];
1.69 deraadt 74: pid_t pid;
1.49 markus 75: char strport[NI_MAXSERV];
1.38 markus 76:
77: /* Convert the port number into a string. */
1.49 markus 78: snprintf(strport, sizeof strport, "%hu", port);
1.38 markus 79:
80: /* Build the final command string in the buffer by making the
81: appropriate substitutions to the given proxy command. */
82: buffer_init(&command);
83: for (cp = proxy_command; *cp; cp++) {
84: if (cp[0] == '%' && cp[1] == '%') {
85: buffer_append(&command, "%", 1);
86: cp++;
87: continue;
88: }
89: if (cp[0] == '%' && cp[1] == 'h') {
90: buffer_append(&command, host, strlen(host));
91: cp++;
92: continue;
93: }
94: if (cp[0] == '%' && cp[1] == 'p') {
1.49 markus 95: buffer_append(&command, strport, strlen(strport));
1.38 markus 96: cp++;
97: continue;
98: }
99: buffer_append(&command, cp, 1);
100: }
101: buffer_append(&command, "\0", 1);
102:
103: /* Get the final command string. */
104: command_string = buffer_ptr(&command);
105:
106: /* Create pipes for communicating with the proxy. */
107: if (pipe(pin) < 0 || pipe(pout) < 0)
108: fatal("Could not create pipes to communicate with the proxy: %.100s",
1.115.2.1! jason 109: strerror(errno));
1.38 markus 110:
111: debug("Executing proxy command: %.500s", command_string);
112:
113: /* Fork and execute the proxy command. */
114: if ((pid = fork()) == 0) {
115: char *argv[10];
116:
117: /* Child. Permanently give up superuser privileges. */
1.103 markus 118: permanently_set_uid(pw);
1.38 markus 119:
120: /* Redirect stdin and stdout. */
121: close(pin[1]);
122: if (pin[0] != 0) {
123: if (dup2(pin[0], 0) < 0)
124: perror("dup2 stdin");
125: close(pin[0]);
126: }
127: close(pout[0]);
128: if (dup2(pout[1], 1) < 0)
129: perror("dup2 stdout");
130: /* Cannot be 1 because pin allocated two descriptors. */
131: close(pout[1]);
132:
133: /* Stderr is left as it is so that error messages get
134: printed on the user's terminal. */
1.89 markus 135: argv[0] = _PATH_BSHELL;
1.38 markus 136: argv[1] = "-c";
137: argv[2] = command_string;
138: argv[3] = NULL;
139:
140: /* Execute the proxy command. Note that we gave up any
141: extra privileges above. */
1.89 markus 142: execv(argv[0], argv);
143: perror(argv[0]);
1.38 markus 144: exit(1);
145: }
146: /* Parent. */
147: if (pid < 0)
148: fatal("fork failed: %.100s", strerror(errno));
149:
150: /* Close child side of the descriptors. */
151: close(pin[0]);
152: close(pout[1]);
153:
154: /* Free the command name. */
155: buffer_free(&command);
156:
157: /* Set the connection file descriptors. */
158: packet_set_connection(pout[0], pin[1]);
1.1 deraadt 159:
1.110 markus 160: /* Indicate OK return */
161: return 0;
1.1 deraadt 162: }
163:
1.39 deraadt 164: /*
165: * Creates a (possibly privileged) socket for use as the ssh connection.
166: */
1.109 itojun 167: static int
1.103 markus 168: ssh_create_socket(struct passwd *pw, int privileged, int family)
1.1 deraadt 169: {
1.105 markus 170: int sock, gaierr;
171: struct addrinfo hints, *res;
1.1 deraadt 172:
1.40 markus 173: /*
174: * If we are running as root and want to connect to a privileged
175: * port, bind our own socket to a privileged port.
176: */
1.38 markus 177: if (privileged) {
178: int p = IPPORT_RESERVED - 1;
1.49 markus 179: sock = rresvport_af(&p, family);
1.38 markus 180: if (sock < 0)
1.55 markus 181: error("rresvport: af=%d %.100s", family, strerror(errno));
182: else
183: debug("Allocated local port %d.", p);
1.105 markus 184: return sock;
185: }
186: /*
187: * Just create an ordinary socket on arbitrary port. We use
188: * the user's uid to create the socket.
189: */
190: temporarily_use_uid(pw);
191: sock = socket(family, SOCK_STREAM, 0);
192: if (sock < 0)
193: error("socket: %.100s", strerror(errno));
194: restore_uid();
195:
196: /* Bind the socket to an alternative local IP address */
197: if (options.bind_address == NULL)
198: return sock;
199:
200: memset(&hints, 0, sizeof(hints));
1.114 markus 201: hints.ai_family = family;
1.105 markus 202: hints.ai_socktype = SOCK_STREAM;
203: hints.ai_flags = AI_PASSIVE;
204: gaierr = getaddrinfo(options.bind_address, "0", &hints, &res);
205: if (gaierr) {
206: error("getaddrinfo: %s: %s", options.bind_address,
207: gai_strerror(gaierr));
208: close(sock);
209: return -1;
210: }
211: if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
212: error("bind: %s: %s", options.bind_address, strerror(errno));
213: close(sock);
214: freeaddrinfo(res);
215: return -1;
1.38 markus 216: }
1.105 markus 217: freeaddrinfo(res);
1.38 markus 218: return sock;
1.1 deraadt 219: }
220:
1.39 deraadt 221: /*
1.49 markus 222: * Opens a TCP/IP connection to the remote server on the given host.
223: * The address of the remote host will be returned in hostaddr.
224: * If port is 0, the default port will be used. If anonymous is zero,
1.39 deraadt 225: * a privileged port will be allocated to make the connection.
226: * This requires super-user privileges if anonymous is false.
227: * Connection_attempts specifies the maximum number of tries (one per
228: * second). If proxy_command is non-NULL, it specifies the command (with %h
229: * and %p substituted for host and port, respectively) to use to contact
230: * the daemon.
1.110 markus 231: * Return values:
232: * 0 for OK
233: * ECONNREFUSED if we got a "Connection Refused" by the peer on any address
234: * ECONNABORTED if we failed without a "Connection refused"
235: * Suitable error messages for the connection failure will already have been
236: * printed.
1.39 deraadt 237: */
1.38 markus 238: int
1.49 markus 239: ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
1.115 markus 240: u_short port, int family, int connection_attempts,
241: int anonymous, struct passwd *pw, const char *proxy_command)
1.1 deraadt 242: {
1.90 markus 243: int gaierr;
244: int on = 1;
1.49 markus 245: int sock = -1, attempt;
1.90 markus 246: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1.49 markus 247: struct addrinfo hints, *ai, *aitop;
1.38 markus 248: struct linger linger;
1.90 markus 249: struct servent *sp;
1.110 markus 250: /*
251: * Did we get only other errors than "Connection refused" (which
252: * should block fallback to rsh and similar), or did we get at least
253: * one "Connection refused"?
254: */
255: int full_failure = 1;
1.38 markus 256:
1.77 deraadt 257: debug("ssh_connect: getuid %u geteuid %u anon %d",
1.115.2.1! jason 258: (u_int) getuid(), (u_int) geteuid(), anonymous);
1.38 markus 259:
260: /* Get default port if port has not been set. */
261: if (port == 0) {
262: sp = getservbyname(SSH_SERVICE_NAME, "tcp");
263: if (sp)
264: port = ntohs(sp->s_port);
265: else
266: port = SSH_DEFAULT_PORT;
267: }
268: /* If a proxy command is given, connect using it. */
269: if (proxy_command != NULL)
1.103 markus 270: return ssh_proxy_connect(host, port, pw, proxy_command);
1.38 markus 271:
272: /* No proxy command. */
273:
1.49 markus 274: memset(&hints, 0, sizeof(hints));
1.115 markus 275: hints.ai_family = family;
1.49 markus 276: hints.ai_socktype = SOCK_STREAM;
277: snprintf(strport, sizeof strport, "%d", port);
278: if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0)
1.50 markus 279: fatal("%s: %.100s: %s", __progname, host,
280: gai_strerror(gaierr));
1.38 markus 281:
1.46 markus 282: /*
283: * Try to connect several times. On some machines, the first time
284: * will sometimes fail. In general socket code appears to behave
285: * quite magically on many machines.
1.110 markus 286: */
287: for (attempt = 0; ;) {
1.38 markus 288: if (attempt > 0)
289: debug("Trying again...");
290:
1.49 markus 291: /* Loop through addresses for this host, and try each one in
1.68 markus 292: sequence until the connection succeeds. */
1.49 markus 293: for (ai = aitop; ai; ai = ai->ai_next) {
294: if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
295: continue;
296: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
297: ntop, sizeof(ntop), strport, sizeof(strport),
298: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
299: error("ssh_connect: getnameinfo failed");
300: continue;
301: }
302: debug("Connecting to %.200s [%.100s] port %s.",
303: host, ntop, strport);
304:
305: /* Create a socket for connecting. */
1.103 markus 306: sock = ssh_create_socket(pw,
1.80 markus 307: !anonymous && geteuid() == 0,
1.49 markus 308: ai->ai_family);
309: if (sock < 0)
1.110 markus 310: /* Any error is already output */
1.49 markus 311: continue;
312:
313: /* Connect to the host. We use the user's uid in the
314: * hope that it will help with tcp_wrappers showing
315: * the remote uid as root.
1.40 markus 316: */
1.103 markus 317: temporarily_use_uid(pw);
1.49 markus 318: if (connect(sock, ai->ai_addr, ai->ai_addrlen) >= 0) {
319: /* Successful connection. */
1.102 markus 320: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 321: restore_uid();
322: break;
1.49 markus 323: } else {
1.110 markus 324: if (errno == ECONNREFUSED)
325: full_failure = 0;
326: log("ssh: connect to address %s port %s: %s",
327: sockaddr_ntop(ai->ai_addr), strport,
328: strerror(errno));
1.38 markus 329: restore_uid();
1.40 markus 330: /*
331: * Close the failed socket; there appear to
332: * be some problems when reusing a socket for
333: * which connect() has already returned an
334: * error.
335: */
1.38 markus 336: close(sock);
337: }
338: }
1.49 markus 339: if (ai)
340: break; /* Successful connection. */
1.1 deraadt 341:
1.110 markus 342: attempt++;
343: if (attempt >= connection_attempts)
344: break;
1.38 markus 345: /* Sleep a moment before retrying. */
346: sleep(1);
347: }
1.49 markus 348:
349: freeaddrinfo(aitop);
350:
1.38 markus 351: /* Return failure if we didn't get a successful connection. */
352: if (attempt >= connection_attempts)
1.110 markus 353: return full_failure ? ECONNABORTED : ECONNREFUSED;
1.38 markus 354:
355: debug("Connection established.");
356:
1.40 markus 357: /*
358: * Set socket options. We would like the socket to disappear as soon
359: * as it has been closed for whatever reason.
360: */
361: /* setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */
1.38 markus 362: linger.l_onoff = 1;
363: linger.l_linger = 5;
1.90 markus 364: setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *)&linger, sizeof(linger));
365:
366: /* Set keepalives if requested. */
367: if (options.keepalives &&
368: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
369: sizeof(on)) < 0)
370: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 371:
372: /* Set the connection. */
373: packet_set_connection(sock, sock);
1.1 deraadt 374:
1.110 markus 375: return 0;
1.59 markus 376: }
377:
1.43 markus 378: /*
1.39 deraadt 379: * Waits for the server identification string, and sends our own
380: * identification string.
381: */
1.109 itojun 382: static void
1.95 itojun 383: ssh_exchange_identification(void)
1.1 deraadt 384: {
1.38 markus 385: char buf[256], remote_version[256]; /* must be same size! */
1.64 markus 386: int remote_major, remote_minor, i, mismatch;
1.38 markus 387: int connection_in = packet_get_connection_in();
388: int connection_out = packet_get_connection_out();
1.93 stevesk 389: int minor1 = PROTOCOL_MINOR_1;
1.38 markus 390:
391: /* Read other side\'s version identification. */
1.75 markus 392: for (;;) {
393: for (i = 0; i < sizeof(buf) - 1; i++) {
1.76 markus 394: int len = atomicio(read, connection_in, &buf[i], 1);
1.75 markus 395: if (len < 0)
396: fatal("ssh_exchange_identification: read: %.100s", strerror(errno));
397: if (len != 1)
398: fatal("ssh_exchange_identification: Connection closed by remote host");
399: if (buf[i] == '\r') {
400: buf[i] = '\n';
401: buf[i + 1] = 0;
402: continue; /**XXX wait for \n */
403: }
404: if (buf[i] == '\n') {
405: buf[i + 1] = 0;
406: break;
407: }
1.38 markus 408: }
1.75 markus 409: buf[sizeof(buf) - 1] = 0;
1.76 markus 410: if (strncmp(buf, "SSH-", 4) == 0)
1.38 markus 411: break;
1.75 markus 412: debug("ssh_exchange_identification: %s", buf);
1.38 markus 413: }
1.59 markus 414: server_version_string = xstrdup(buf);
1.38 markus 415:
1.40 markus 416: /*
417: * Check that the versions match. In future this might accept
418: * several versions and set appropriate flags to handle them.
419: */
1.59 markus 420: if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
421: &remote_major, &remote_minor, remote_version) != 3)
1.38 markus 422: fatal("Bad remote protocol version identification: '%.100s'", buf);
423: debug("Remote protocol version %d.%d, remote software version %.100s",
1.115.2.1! jason 424: remote_major, remote_minor, remote_version);
1.38 markus 425:
1.59 markus 426: compat_datafellows(remote_version);
1.64 markus 427: mismatch = 0;
1.59 markus 428:
1.115.2.1! jason 429: switch (remote_major) {
1.64 markus 430: case 1:
431: if (remote_minor == 99 &&
432: (options.protocol & SSH_PROTO_2) &&
433: !(options.protocol & SSH_PROTO_1_PREFERRED)) {
434: enable_compat20();
435: break;
436: }
437: if (!(options.protocol & SSH_PROTO_1)) {
438: mismatch = 1;
439: break;
440: }
441: if (remote_minor < 3) {
442: fatal("Remote machine has too old SSH software version.");
1.81 markus 443: } else if (remote_minor == 3 || remote_minor == 4) {
1.64 markus 444: /* We speak 1.3, too. */
445: enable_compat13();
1.81 markus 446: minor1 = 3;
1.64 markus 447: if (options.forward_agent) {
448: log("Agent forwarding disabled for protocol 1.3");
449: options.forward_agent = 0;
450: }
451: }
452: break;
453: case 2:
454: if (options.protocol & SSH_PROTO_2) {
455: enable_compat20();
456: break;
1.38 markus 457: }
1.64 markus 458: /* FALLTHROUGH */
1.68 markus 459: default:
1.64 markus 460: mismatch = 1;
461: break;
1.38 markus 462: }
1.64 markus 463: if (mismatch)
1.38 markus 464: fatal("Protocol major versions differ: %d vs. %d",
1.64 markus 465: (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
466: remote_major);
1.38 markus 467: /* Send our own protocol version identification. */
468: snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n",
1.64 markus 469: compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
1.81 markus 470: compat20 ? PROTOCOL_MINOR_2 : minor1,
1.59 markus 471: SSH_VERSION);
1.45 deraadt 472: if (atomicio(write, connection_out, buf, strlen(buf)) != strlen(buf))
1.38 markus 473: fatal("write: %.100s", strerror(errno));
1.59 markus 474: client_version_string = xstrdup(buf);
475: chop(client_version_string);
476: chop(server_version_string);
477: debug("Local version string %.100s", client_version_string);
1.1 deraadt 478: }
479:
1.96 markus 480: /* defaults to 'no' */
1.109 itojun 481: static int
1.112 markus 482: confirm(const char *prompt)
1.1 deraadt 483: {
1.115.2.1! jason 484: const char *msg, *again = "Please type 'yes' or 'no': ";
! 485: char *p;
! 486: int ret = -1;
1.96 markus 487:
488: if (options.batch_mode)
489: return 0;
1.115.2.1! jason 490: for (msg = prompt;;msg = again) {
! 491: p = read_passphrase(msg, RP_ECHO);
! 492: if (p == NULL ||
! 493: (p[0] == '\0') || (p[0] == '\n') ||
! 494: strncasecmp(p, "no", 2) == 0)
! 495: ret = 0;
! 496: if (strncasecmp(p, "yes", 3) == 0)
! 497: ret = 1;
! 498: if (p)
! 499: xfree(p);
! 500: if (ret != -1)
! 501: return ret;
1.1 deraadt 502: }
503: }
504:
1.39 deraadt 505: /*
1.108 markus 506: * check whether the supplied host key is valid, return -1 if the key
507: * is not valid. the user_hostfile will not be updated if 'readonly' is true.
1.39 deraadt 508: */
1.46 markus 509:
1.109 itojun 510: static int
1.70 markus 511: check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
1.108 markus 512: int readonly, const char *user_hostfile, const char *system_hostfile)
1.1 deraadt 513: {
1.58 markus 514: Key *file_key;
1.72 markus 515: char *type = key_type(host_key);
1.46 markus 516: char *ip = NULL;
1.100 markus 517: char hostline[1000], *hostp, *fp;
1.38 markus 518: HostStatus host_status;
519: HostStatus ip_status;
1.49 markus 520: int local = 0, host_ip_differ = 0;
521: char ntop[NI_MAXHOST];
1.115.2.1! jason 522: char msg[1024];
! 523: int len, host_line, ip_line;
1.85 markus 524: const char *host_file = NULL, *ip_file = NULL;
1.49 markus 525:
526: /*
527: * Force accepting of the host key for loopback/localhost. The
528: * problem is that if the home directory is NFS-mounted to multiple
529: * machines, localhost will refer to a different machine in each of
530: * them, and the user will get bogus HOST_CHANGED warnings. This
531: * essentially disables host authentication for localhost; however,
532: * this is probably not a real problem.
533: */
1.70 markus 534: /** hostaddr == 0! */
1.49 markus 535: switch (hostaddr->sa_family) {
536: case AF_INET:
1.108 markus 537: local = (ntohl(((struct sockaddr_in *)hostaddr)->
538: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
1.49 markus 539: break;
540: case AF_INET6:
1.108 markus 541: local = IN6_IS_ADDR_LOOPBACK(
542: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
1.49 markus 543: break;
544: default:
545: local = 0;
546: break;
547: }
1.111 markus 548: if (options.no_host_authentication_for_localhost == 1 && local &&
549: options.host_key_alias == NULL) {
1.88 markus 550: debug("Forcing accepting of host key for "
551: "loopback/localhost.");
1.108 markus 552: return 0;
1.49 markus 553: }
1.42 markus 554:
555: /*
1.88 markus 556: * We don't have the remote ip-address for connections
557: * using a proxy command
1.42 markus 558: */
1.84 markus 559: if (options.proxy_command == NULL) {
560: if (getnameinfo(hostaddr, hostaddr->sa_len, ntop, sizeof(ntop),
1.86 markus 561: NULL, 0, NI_NUMERICHOST) != 0)
1.84 markus 562: fatal("check_host_key: getnameinfo failed");
563: ip = xstrdup(ntop);
564: } else {
565: ip = xstrdup("<no hostip for proxy command>");
1.86 markus 566: }
1.88 markus 567: /*
568: * Turn off check_host_ip if the connection is to localhost, via proxy
569: * command or if we don't have a hostname to compare with
570: */
571: if (options.check_host_ip &&
572: (local || strcmp(host, ip) == 0 || options.proxy_command != NULL))
573: options.check_host_ip = 0;
1.86 markus 574:
575: /*
576: * Allow the user to record the key under a different name. This is
577: * useful for ssh tunneling over forwarded connections or if you run
578: * multiple sshd's on different ports on the same machine.
579: */
580: if (options.host_key_alias != NULL) {
581: host = options.host_key_alias;
582: debug("using hostkeyalias: %s", host);
1.84 markus 583: }
1.38 markus 584:
1.46 markus 585: /*
586: * Store the host key from the known host file in here so that we can
587: * compare it with the key for the IP address.
588: */
1.58 markus 589: file_key = key_new(host_key->type);
1.38 markus 590:
1.40 markus 591: /*
592: * Check if the host key is present in the user\'s list of known
593: * hosts or in the systemwide list.
594: */
1.85 markus 595: host_file = user_hostfile;
1.108 markus 596: host_status = check_host_in_hostfile(host_file, host, host_key,
1.115.2.1! jason 597: file_key, &host_line);
1.85 markus 598: if (host_status == HOST_NEW) {
599: host_file = system_hostfile;
1.108 markus 600: host_status = check_host_in_hostfile(host_file, host, host_key,
601: file_key, &host_line);
1.85 markus 602: }
1.40 markus 603: /*
604: * Also perform check for the ip address, skip the check if we are
605: * localhost or the hostname was an ip address to begin with
606: */
1.88 markus 607: if (options.check_host_ip) {
1.58 markus 608: Key *ip_key = key_new(host_key->type);
1.38 markus 609:
1.85 markus 610: ip_file = user_hostfile;
1.108 markus 611: ip_status = check_host_in_hostfile(ip_file, ip, host_key,
612: ip_key, &ip_line);
1.85 markus 613: if (ip_status == HOST_NEW) {
614: ip_file = system_hostfile;
1.108 markus 615: ip_status = check_host_in_hostfile(ip_file, ip,
616: host_key, ip_key, &ip_line);
1.85 markus 617: }
1.38 markus 618: if (host_status == HOST_CHANGED &&
1.58 markus 619: (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key)))
1.38 markus 620: host_ip_differ = 1;
621:
1.58 markus 622: key_free(ip_key);
1.38 markus 623: } else
624: ip_status = host_status;
625:
1.58 markus 626: key_free(file_key);
1.38 markus 627:
628: switch (host_status) {
629: case HOST_OK:
630: /* The host is known and the key matches. */
1.72 markus 631: debug("Host '%.200s' is known and matches the %s host key.",
632: host, type);
1.85 markus 633: debug("Found key in %s:%d", host_file, host_line);
1.88 markus 634: if (options.check_host_ip && ip_status == HOST_NEW) {
1.108 markus 635: if (readonly)
636: log("%s host key for IP address "
637: "'%.128s' not in list of known hosts.",
638: type, ip);
639: else if (!add_host_to_hostfile(user_hostfile, ip,
1.115.2.1! jason 640: host_key))
1.108 markus 641: log("Failed to add the %s host key for IP "
642: "address '%.128s' to the list of known "
643: "hosts (%.30s).", type, ip, user_hostfile);
1.88 markus 644: else
1.108 markus 645: log("Warning: Permanently added the %s host "
646: "key for IP address '%.128s' to the list "
647: "of known hosts.", type, ip);
1.38 markus 648: }
649: break;
650: case HOST_NEW:
1.108 markus 651: if (readonly)
652: goto fail;
1.38 markus 653: /* The host is new. */
654: if (options.strict_host_key_checking == 1) {
1.108 markus 655: /*
656: * User has requested strict host key checking. We
657: * will not add the host key automatically. The only
658: * alternative left is to abort.
659: */
660: error("No %s host key is known for %.200s and you "
661: "have requested strict checking.", type, host);
662: goto fail;
1.38 markus 663: } else if (options.strict_host_key_checking == 2) {
664: /* The default */
1.100 markus 665: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1.115.2.1! jason 666: snprintf(msg, sizeof(msg),
1.108 markus 667: "The authenticity of host '%.200s (%s)' can't be "
668: "established.\n"
1.72 markus 669: "%s key fingerprint is %s.\n"
1.108 markus 670: "Are you sure you want to continue connecting "
671: "(yes/no)? ", host, ip, type, fp);
1.100 markus 672: xfree(fp);
1.115.2.1! jason 673: if (!confirm(msg))
1.108 markus 674: goto fail;
1.38 markus 675: }
1.88 markus 676: if (options.check_host_ip && ip_status == HOST_NEW) {
1.38 markus 677: snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
678: hostp = hostline;
679: } else
680: hostp = host;
681:
1.108 markus 682: /*
683: * If not in strict mode, add the key automatically to the
684: * local known_hosts file.
685: */
1.70 markus 686: if (!add_host_to_hostfile(user_hostfile, hostp, host_key))
1.108 markus 687: log("Failed to add the host to the list of known "
688: "hosts (%.500s).", user_hostfile);
1.38 markus 689: else
1.108 markus 690: log("Warning: Permanently added '%.200s' (%s) to the "
691: "list of known hosts.", hostp, type);
1.38 markus 692: break;
693: case HOST_CHANGED:
694: if (options.check_host_ip && host_ip_differ) {
695: char *msg;
696: if (ip_status == HOST_NEW)
697: msg = "is unknown";
698: else if (ip_status == HOST_OK)
699: msg = "is unchanged";
700: else
701: msg = "has a different value";
702: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
703: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
704: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 705: error("The %s host key for %s has changed,", type, host);
1.38 markus 706: error("and the key for the according IP address %s", ip);
707: error("%s. This could either mean that", msg);
708: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 709: error("and its host key have changed at the same time.");
1.88 markus 710: if (ip_status != HOST_NEW)
1.85 markus 711: error("Offending key for IP in %s:%d", ip_file, ip_line);
1.38 markus 712: }
713: /* The host key has changed. */
1.100 markus 714: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1.38 markus 715: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.47 markus 716: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1.38 markus 717: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
718: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
719: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1.72 markus 720: error("It is also possible that the %s host key has just been changed.", type);
1.87 markus 721: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1.100 markus 722: type, fp);
1.38 markus 723: error("Please contact your system administrator.");
724: error("Add correct host key in %.100s to get rid of this message.",
1.87 markus 725: user_hostfile);
1.85 markus 726: error("Offending key in %s:%d", host_file, host_line);
1.100 markus 727: xfree(fp);
1.38 markus 728:
1.40 markus 729: /*
730: * If strict host key checking is in use, the user will have
731: * to edit the key manually and we can only abort.
732: */
1.108 markus 733: if (options.strict_host_key_checking) {
734: error("%s host key for %.200s has changed and you have "
735: "requested strict checking.", type, host);
736: goto fail;
737: }
1.38 markus 738:
1.40 markus 739: /*
740: * If strict host key checking has not been requested, allow
741: * the connection but without password authentication or
742: * agent forwarding.
743: */
1.38 markus 744: if (options.password_authentication) {
1.108 markus 745: error("Password authentication is disabled to avoid "
746: "man-in-the-middle attacks.");
1.38 markus 747: options.password_authentication = 0;
748: }
749: if (options.forward_agent) {
1.108 markus 750: error("Agent forwarding is disabled to avoid "
751: "man-in-the-middle attacks.");
1.38 markus 752: options.forward_agent = 0;
1.83 markus 753: }
754: if (options.forward_x11) {
1.108 markus 755: error("X11 forwarding is disabled to avoid "
756: "man-in-the-middle attacks.");
1.83 markus 757: options.forward_x11 = 0;
758: }
1.108 markus 759: if (options.num_local_forwards > 0 ||
760: options.num_remote_forwards > 0) {
761: error("Port forwarding is disabled to avoid "
762: "man-in-the-middle attacks.");
763: options.num_local_forwards =
1.115.2.1! jason 764: options.num_remote_forwards = 0;
1.38 markus 765: }
1.40 markus 766: /*
767: * XXX Should permit the user to change to use the new id.
768: * This could be done by converting the host key to an
769: * identifying sentence, tell that the host identifies itself
770: * by that sentence, and ask the user if he/she whishes to
771: * accept the authentication.
772: */
1.38 markus 773: break;
1.88 markus 774: }
775:
776: if (options.check_host_ip && host_status != HOST_CHANGED &&
777: ip_status == HOST_CHANGED) {
1.115.2.1! jason 778: snprintf(msg, sizeof(msg),
! 779: "Warning: the %s host key for '%.200s' "
! 780: "differs from the key for the IP address '%.128s'"
! 781: "\nOffending key for IP in %s:%d",
! 782: type, host, ip, ip_file, ip_line);
! 783: if (host_status == HOST_OK) {
! 784: len = strlen(msg);
! 785: snprintf(msg + len, sizeof(msg) - len,
! 786: "\nMatching host key in %s:%d",
! 787: host_file, host_line);
! 788: }
1.88 markus 789: if (options.strict_host_key_checking == 1) {
1.115.2.1! jason 790: log(msg);
1.108 markus 791: error("Exiting, you have requested strict checking.");
792: goto fail;
1.88 markus 793: } else if (options.strict_host_key_checking == 2) {
1.115.2.1! jason 794: strlcat(msg, "\nAre you sure you want "
! 795: "to continue connecting (yes/no)? ", sizeof(msg));
! 796: if (!confirm(msg))
1.108 markus 797: goto fail;
1.115.2.1! jason 798: } else {
! 799: log(msg);
1.88 markus 800: }
1.38 markus 801: }
1.82 provos 802:
803: xfree(ip);
1.108 markus 804: return 0;
805:
806: fail:
807: xfree(ip);
808: return -1;
809: }
810:
811: int
812: verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
813: {
814: struct stat st;
815:
816: /* return ok if the key can be found in an old keyfile */
817: if (stat(options.system_hostfile2, &st) == 0 ||
818: stat(options.user_hostfile2, &st) == 0) {
819: if (check_host_key(host, hostaddr, host_key, /*readonly*/ 1,
820: options.user_hostfile2, options.system_hostfile2) == 0)
821: return 0;
822: }
823: return check_host_key(host, hostaddr, host_key, /*readonly*/ 0,
824: options.user_hostfile, options.system_hostfile);
1.51 markus 825: }
1.70 markus 826:
1.51 markus 827: /*
828: * Starts a dialog with the server, and authenticates the current user on the
829: * server. This does not need any extra privileges. The basic connection
830: * to the server must already have been established before this is called.
831: * If login fails, this function prints an error and never returns.
832: * This function does not require super-user privileges.
833: */
834: void
1.104 markus 835: ssh_login(Key **keys, int nkeys, const char *orighost,
1.103 markus 836: struct sockaddr *hostaddr, struct passwd *pw)
1.51 markus 837: {
838: char *host, *cp;
1.70 markus 839: char *server_user, *local_user;
840:
841: local_user = xstrdup(pw->pw_name);
842: server_user = options.user ? options.user : local_user;
1.51 markus 843:
844: /* Convert the user-supplied hostname into all lowercase. */
845: host = xstrdup(orighost);
846: for (cp = host; *cp; cp++)
847: if (isupper(*cp))
848: *cp = tolower(*cp);
849:
850: /* Exchange protocol version identification strings with the server. */
851: ssh_exchange_identification();
852:
853: /* Put the connection into non-blocking mode. */
854: packet_set_nonblocking();
855:
856: /* key exchange */
857: /* authenticate user */
1.59 markus 858: if (compat20) {
859: ssh_kex2(host, hostaddr);
1.104 markus 860: ssh_userauth2(local_user, server_user, host, keys, nkeys);
1.59 markus 861: } else {
862: ssh_kex(host, hostaddr);
1.104 markus 863: ssh_userauth1(local_user, server_user, host, keys, nkeys);
1.59 markus 864: }
1.97 markus 865: }
866:
867: void
868: ssh_put_password(char *password)
869: {
870: int size;
871: char *padded;
872:
1.99 deraadt 873: if (datafellows & SSH_BUG_PASSWORDPAD) {
1.107 markus 874: packet_put_cstring(password);
1.99 deraadt 875: return;
876: }
1.97 markus 877: size = roundup(strlen(password) + 1, 32);
878: padded = xmalloc(size);
879: memset(padded, 0, size);
880: strlcpy(padded, password, size);
881: packet_put_string(padded, size);
882: memset(padded, 0, size);
883: xfree(padded);
1.1 deraadt 884: }
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